Cleared website data, pop ups still appearing

For the last few days, I’ve had a ton of pop up ads saying I’ve won this or that appearing in safari (running on a 6s with iOS 11.1.2). I have the “block pop up ads” setting turned on, and I’ve cleared my website history and data multiple times, but they keep showing up.

If anyone has any idea how to help stop this, it would be much appreciated!